1. Field of the Invention
The present invention relates to an image recording method and apparatus for recording a plurality of non-synchronous image data obtained by a plurality of imaging devices, such as endoscope devices.
2. Description of the Background Art
Recently, hospitals grow larger the number of large hospitals employing endoscope devices is also increasing. In such hospitals, image data obtained by a plurality of endoscope devices are usually recorded by a single image recording apparatus.
Now, in the very common situation in which image recording apparatus is used, if the mutually non-synchronous outputs of the plurality of the endoscope devices are simply connected to the image recording device, reliable image recording cannot be carried out because there is a possibility for the image data from more than one endoscope to get mixed up on a single recorded image.
To cope with this problem, a conventional image recording apparatus has, as shown in FIG. 1, so called time base correctors (TBC) 2a to 2c each of which is provided for each one of the plurality (three in this example) of endoscope devices 1a to 1c, where the image data from each one of the endoscope devices 1a to 1c are synchronized with an externally generated synchronous signal at each of the time base correctors 2a to 2c before being recorded. Such a conventional image recording apparatus also has an image switching device 3 for selectively transmitting one of the synchronized outputs from the time base correctors 2a to 2c to an image recording device 4 for actually recording the image data, such that the mixing up of more than one image data in a single recorded image can be prevented.
In further detail, the operation of this type of a conventional image recording apparatus will be described with reference to the timing charts of FIG. 2 to FIG. 4.
First, in the conventional image recording apparatus of FIG. 1, the endoscope devices 1a to 1c output the image data in the timings shown by (1), (2), and (3) in FIG. 2, respectively. For example, the endoscope device 1a outputs the image data for the images A1, A2, and so on obtained by its imaging operation in the timing shown by (1) where the image data contains the sequence of the odd field of an image A1 (A1O), the even field of the image Al (A1E), the odd field of an image A2 (A2O), the even field of the image A2 (A2E), and so on, each of which is accompanied by a vertical synchronous pulse. Similarly, the endoscope device 1b outputs the image data for the images B1, B2, and so on in the timing shown by (2), while the endoscope device 1c outputs the image data for the images C1, C2, and so on in the timing shown by (3). Here, as should be clear from FIG. 2 that the vertical synchronous pulses in the image data from the endoscope devices 1a, 1b, and 1c are non-synchronous, i.e., each endoscope device is outputting the image data at its own timings not related to the output timings of the other endoscope devices.
These image data outputted from the endoscope devices 1a to 1c are subsequently synchronized with the externally given synchronous signal at each of the time base correctors 2a to 2c, so that as shown in FIG. 3, all of the vertical synchronous pulses in the outputs of the time base correctors 2a to 2c shown by (2) to (4) in FIG. 3 are synchronous to the external synchronous signal shown by (1) in FIG. 3. These synchronized outputs of the time base collectors 2a to 2c are then supplied to the image switching device 3 where an arbitrary one of the synchronized outputs from the time base collectors 2a to 2c is selectively transmitted to the image recording device 4 and recorded there.
Now, consider an exemplary case shown in FIG. 4, in which an operator using the endoscope device 1a and another operator using the endoscope device 1b simultaneously operated their respective endoscope device to generate freeze signals shown by (1) and (2) in FIG. 4 to the time base correctors 2a and 2b, so as to activate the recording of the image taken by their respective endoscope device at that point. In this case, the time base correctors 2a and 2b output the synchronized outputs for the frozen images A1 and B1 as shown by (3) and (4) in FIG. 4. Then, according to the image switching signal shown by (5) in FIG. 4, the image switching device 3 selects the image data for the image A1 from the time base correctors 2a first in order to have the image data for the image A1 recorded in the image recording device 4 as shown by (6) in FIG. 4, and then selects the image data for the image B1 from the time base correctors 2b next, in order to have the image data for the image B1 recorded in the image recording device 4 as shown by (6) in FIG. 4.
In this manner, the reliable recording of the image data from the plurality of endoscope devices has been achieved by a conventional image recording apparatus.
However, such a conventional image recording apparatus has the problem in that the time base correctors must be provided for each one of the plurality of endoscope devices involved, so that a large space is required for the image recording apparatus equipped with a plurality of time base corrector. Moreover, the time base corrector is a fairly expensive circuit device, so that the image recording apparatus becomes increasingly expensive as the number of endoscope devices increases.